1. Minerals

2. What properties are used to identify minerals?
Essential Question
What properties are used to identify minerals?

3. What is a Mineral?
Naturally-formed solid substance with a crystal structure
Pyromorphite

4. What do all minerals have in common?
Formed by natural processes.
Are Inorganic
Element or compound that has a unique chemical composition (makeup)
Have a crystalline shape- they have a definite volume and shape

5. How are Minerals classified or grouped?
Beryl (Emerald)
Minerals are defined by their physical properties.
90 elements occur naturally in the Earth’s crust
About 98% of the crust is made of only 8 of these elements
The most common minerals belong to the Silicates
Amethyst
Calcite

6. Contain oxygen & silicon The most abundant group of minerals
Mineral Group
Characteristics
Examples
Silicates
Contain oxygen & silicon
The most abundant group of minerals
Quartz Mica
Feldspar
MICA
Quartz

7. How do minerals form? There are 2 ways that crystals form:
The cooling of hot, liquid rock called magma causes compounds to combine
Magma cools slowly = large Crystals
Magma cools quickly = small crystals
The evaporation of water that has minerals dissolved in it

8. How do we identify Minerals?
We look at Physical Properties
These include:
Color/Appearance
Luster
Streak
Hardness
Cleavage/Fracture

9. Physical Properties of Minerals (can be used to identify the mineral)
Color
Can be misleading
Many minerals will have a similar appearance, but will have different impurities

10. Physical Properties of Minerals (can be used to identify the mineral)
Luster
Luster refers to the way a mineral reflects light from its surface.
Metallic = shiny like metal
Non-metallic = dull, non-shiny surface
Pyrite has a metallic luster
Calcite has a non-metallic luster

11. Physical Properties of Minerals (can be used to identify the mineral)
Streak
The color of the powdered form of the mineral
The color of the streak can be different than the mineral
Minerals must be softer than the streak plate

12. Streak…can help identify quartz
BUT...

13. Physical Properties of Minerals (can be used to identify the mineral)
Hardness
How easily a mineral scratches materials
Mohs Hardness Scale
Scale from 1 (softest) to 10 (hardest)
Test by seeing if the mineral can scratch different objects (like human fingernail, copper, penny, glass, steel file)

14. Physical Properties of Minerals (can be used to identify the mineral)
Cleavage & Fracture
The way the mineral breaks
Cleavage—minerals break along smooth, flat surfaces and every fragment has the same general shape
Fracture—minerals that break at random with rough or jagged edges

15. Cleavage or Fracture? 1. 2. 3. 4.

16. Review What is a Mineral?
Name 2 things that all minerals have in common?
The mineral group, Silicates, is made up of what two elements?
How are minerals identified?
A naturally occurring solid with a crystal structure
Inorganic, Crystalline Structure, Formed Naturally, Unique Chemical Composition
Oxygen and Silicon
Color, Luster, Streak, Hardness, Cleavage, Fracture